What is visually different in the ecg reading from normal sinus rhythm?

The difference that can be found are:

Nodal rhythm: you can see the absence of the p wave (the first electric signal of an ECG)

Heart block: Heart block is a delay in the conduction of the electrical impulse through the atrioventricular node, the His bundle, or both branches, all located between the atria and the ventricles. There is a gap between the p and the rest of the ECG.

Atrial flutter: Designate atrial fibrillation whose amplitude, relative regularity and low frequency of the ripples are close to atrial flutter. Nevertheless, the f-waves are slightly irregular and rather positive in DII-III-VF shunts (unlike common atrial flutter). This aspect is in favor of a rather recent FA.

Atrial fibrillation: We observe:

*An absence of sinus wave P

*Auriculograms that vary anarchically in amplitude, shape, and frequency. They form a ripple of the baseline that may be relatively broad or barely visible (in aged forms), sometimes observed selectively in V1. These f waves can be confused with artifacts.

*Irregular RR intervals. 

Ventricular fibrillation: an Anarchic electrical activity of the ventricular myocardium. The resulting total desynchronization is responsible for circulatory arrest (asystole).

the glands which are associated with each description is given below:

since there are no options posted i'll give you a few examples.

a dolphin's flipper, bird's wing, cat's leg.